Occupational Exposure of Dioxins in Taiwan

Transcription

1 Occupational Exposure of Dioxins in Taiwan T. S. Shih 1, C. C. Lee 2 1 Institute of Occupational Safety and Health, Council of Labor Affairs, Taiwan 2 Research Center of Environmental Trace Toxic Substances, Medical College, National Cheng Kung University, Taiwan

2 Outline Introduction Objectives Materials and Methods Results and Discussion Conclusions 2

3 Introduction Dioxins are toxic substances unintentionally generated as the by-products of human activities: for example, municipal waste incinerators (MWIs), metal smelters, high temperature industrial processes, organic chloride pesticide plants, paper and pulp industries, and wool-treating factories. Fiedler et al., 1997; Patandin et al.,

4 Introduction Taiwan EPA have compiled inventories of dioxins emission sources that identify electric arc furnaces, primary ferrous metal smelters, municipal waste incineration, zinc oxide recovery process and other metallurgical processes as major contributors. 4

5 Introduction Cement kiln process, 1% Zinc oxide recovery process, 13% Others, 12% Electric arc furnaces, 30% Solid waste incineration, 14% Secondary nonferrous metal smelter, 6% Primary ferrous metal smelter, 24% 5

6 Introduction 31 municipal waste incinerators (MWIs) will be set up before 2007, and now 22 MWIs are currently operating in Taiwan. It is highly likely that many temporary and intermittent maintenance workers are exposed to slag and fly ash while maintaining and cleaning firebrick inside the furnace or repairing air-pollution-control devices, or both. 6

7 Introduction Some studies have proved the accumulation of dioxins in the serum of incinerator workers, but few studies have focused on temporary employees who worked intermittently and periodically in maintenance and clean-up of firebrick inside the furnaces and/or repair of air-pollution-control devices around different incinerators. 7

8 Introduction Electric arc furnaces (EAF) and secondary nonferrous metal smelters (aluminum and copper smelters) primarily utilize the scrap materials as raw materials. Those scrap materials may contain organic impurities, such as plastics, organic chloride chemicals, and dioxins, which are formed during the smelting processes. 8

9 Introduction Although a few studies have indicted the exposure status and adverse health effects from the workers at municipal waste incinerators possible with dioxins exposure, little is known about the occupational exposure levels in the workers at metallurgical smelting processes potential with much more dioxins exposure. 9

10 Introduction Municipal Waste Incinerator Maintenance Electric arc furnaces Secondary aluminum smelters Secondary copper smeltesr Total No. of factories of different occupation in Taiwan Total No. of workers of different occupation in Taiwan unknown 18,000 8,000 3,000 10

11 Objectives We aimed to assess the distribution of serum dioxins levels and the congener patterns of employees in the beginning of periodical maintenance and after a month's work on the incinerators, and to assess increases in the serum dioxins levels after each round of maintenance in temporary and intermittent workers. We aimed to assess the associations between serum dioxins levels of workers and ambient dioxins levels in the working environment for workers of secondary metal smelters. 11

12 Materials and Methods Subject Selection and Serum Collection For biological monitoring, serum samples of workers were recruited separately from 4 incinerators (n=35), 1 EAF plant (n=45), 2 secondary copper smelters (n=46), and 2 secondary aluminum smelters (n=43) in Taiwan. 12

13 Materials and Methods Subject Selection and Serum Collection After signing a consent form and the day after completing an overnight fast, each study participant provided 60 ml of venous blood. Blood samples were drawn into chemically clean tubes containing no anticoagulants, and serum samples, obtained after centrifugation, were stored at 70 C until analysis. One month after the maintenance work, another 60 ml blood was taken from each participant for dioxins analysis. 13

14 Materials and Methods Serum Sample Clean-ups and HRGC/HRMS Analysis of Dioxins Seventeen 2,3,7,8-substituted dioxins were measured in serum samples, using isotope dilution HRGC/HRMS. Each serum sample was spiked with a mixture containing fifteen 13 C 12 -dioxins standards as defined in USEPA Method

15 Materials and Methods Serum Sample Clean-ups and HRGC/HRMS Analysis of Dioxins Each analytical run consisted of a method blank, a quality control, and seven unknown samples for quality assurance and quality control. All dioxins were adjusted to the lipid content analyzed from the corresponding samples and were reported as pg WHO-TEQ/g lipid. 15

16 Materials and Methods Ambient Sampling in the Working Environments of metal smelters Two ambient air samples from the working environment were collected for dioxins analysis, one from near the furnace and the other inside the casting department in each plant. Ambient air samples were collected with PS-1 samplers, the sampling time was set as 48 hours. 16

17 Materials and Methods Ambient Sample Clean-ups and HRGC/HRMS Analysis of Dioxins Sample preparation was done according to the method TO-9A developed by USEPA. The extracted sample was washed with H 2 SO 4 and then extracted with hexane. Sample clean-up was accomplished with acidic silica-gel column, alumina column and activated carbon column, and concentrated with N 2 gas. 17

18 Materials and Methods Ambient Sample Clean-ups and HRGC/HRMS Analysis of Dioxins The quantification of dioxins was performed with HRGC/HRMS with a DB-5 MS column. Seventeen toxic 2,3,7,8-substituted congeners were quantified. 18

19 Results and Discussion Table 1 Demographic information of MWI maintenance workers Variables Distribution Sex Male 34 (97%) Female 1 (3%) Age (years) 41.8 (7.5) Smoking status Never smoked 9 (25.7%) Smokers 26 (74.3%) Alcohol intake (> twice per week) No 11 (31.4%) Yes 24 (68.6%) Mean (standard deviation) 19

20 Results and Discussion r = , p = < nd : pg WHO-TEQ/g lipid st : pg WHO-TEQ/g lipid Fig. 1. Correlation of serum dioxins levels before and after annual maintenance of incinerators (Wilcoxon matched pairs test). 20

21 Results and Discussion Table 2 Differences in serum dioxins levels before and after periodic maintenance work Previous MWI Before After P value work experience Mean # SD Mean SD No (N = 16) * Yes (N = 18) P value 0.008* 0.035* Mann-Whitney U test; Wilcoxon matched pairs test; # Serum dioxins levels (pg WHO-TEQ/g lipid) 21

22 Results and Discussion Table 3 Differences in congener patterns of serum dioxins levels in workers before and after periodic maintenance of incinerators Congeners Pre-periodic maintenance After periodic maintenance pg /g lipid* P value 2,3,7,8-TCDF 1.99 ( ) 0.28 ( ) ,2,3,7,8-PeCDF 2.44 ( ) 2.08 ( ) ,3,4,7,8- PeCDF ( ) ( ) ,2,3,4,7,8-HxCDF 8.22 ( ) 9.02 ( ) ,2,3,6,7,8- HxCDF 9.32 ( ) 9.97 ( ) ,3,4,6,7,8- HxCDF 4.33 ( ) 9.69 ( ) 0.008* 1,2,3,4,7,8,9- HxCDF 1.69 ( ) 1.21 ( ) ,2,3,4,6,7,8- HxCDF ( ) ( ) 0.008* 1,2,3,4,7,8,9- HxCDF 4.01 ( ) 3.51 ( ) OCDF ( ) ( ) ,3,7,8-TCDD 2.55 ( ) 3.48 ( ) 0.015* 1,2,3,7,8-PeCDD 5.52 ( ) 6.22 ( ) ,2,3,4,7,8-HxCDD 3.60 ( ) 3.26 ( ) ,2,3,6,7,8- HxCDD 20.3 ( ) ( ) ,2,3,7,8,9- HxCDD 5.54 ( ) 5.89 ( ) ,2,3,4,6,7,8-HpCDD ( ) ( ) OCDD ( ) ( ) PCDD/Fs ( ) ( ) Dioxins (WHO-TEQ) ( ) ( ) 0.002* : Wilcoxon matched pairs test, * Mean (min-max) 22

23 Results and Discussion Never Ever Difference between pre- and after work (%) 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8- PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8- HxCDF 2,3,4,6,7,8- HxCDF 1,2,3,4,7,8,9- HxCDF 1,2,3,4,6,7,8- HxCDF 1,2,3,4,7,8,9- HxCDF OCDF 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8- HxCDD 1,2,3,7,8,9- HxCDD 1,2,3,4,6,7,8-HpCDD OCDD Congeners Fig. 2. The differences in change of serum dioxins levels of 17 congeners after the annual maintenance between the workers who have never or ever participates the kind of job. Congener pattern between pre- and post-work = [difference of % in each congener to total dioxins (pg/g lipid) levels in pre-work after work finished] /pre-work 100%. 23

24 Results and Discussion The present study confirms significant increased of serum dioxins levels in temporary workers after even short-term exposure to slag and fly ash in municipal waste incinerators through annual maintenance work. 24

25 Results and Discussion Table 4 Demographic distribution of the workers in 3 metallurgical industries Plant Al Cu EAF N P value # Age ( ) ( ) ( ) Sex ratio Men Women 39 (90.7) 4 (9.3) 45 (97.8) 1 (2.2) 45 (100) Body fat (%) 24.2 ( ) BMI 24.8 ( ) work period 10.4 ( ) : mean (minium-maximun) : Number (% of total subjects) # :analyzed by Wilcoxon test 22.0 ( ) 25.3 ( ) 8.8 ( ) 21.1 ( ) 23.5 ( ) 10.1 ( ) 0.011*

26 Table 5 Congener profile of serum dioxins levels (pg WHO-TEQ/g lipid) among 3 industries Industries Al Cu EAF N P value 2,3,7,8-TCDF * 1,2,3,7,8-PeCDF * 2,3,4,7,8-PeCDF * 1,2,3,4,7,8-HxCDF <0.0001** 1,2,3,6,7,8-HxCDF <0.0001** 2,3,4,6,7,8-HxCDF <0.0001** 1,2,3,7,8,9-HxCDF <0.0001** 1,2,3,4,6,7,8-HpCDF <0.0001** 1,2,3,4,7,8,9-HpCDF <0.0001** OCDF <0.0001** 2,3,7,8-TCDD ,2,3,7,8-PeCDD ,2,3,4,7,8-HxCDD * 1,2,3,6,7,8-HxCDD ,2,3,7,8,9-HxCDD ,2,3,4,6,7,8-HpCDD OCDD * 17 Dioxins *: p value< 0.05, **: p value <

27 Results and Discussion Al-serum Al-air %of pg levels 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD 0 Congeners Figure 3 Comparison of dioxins levels in ambient air and serum of workers in aluminum smelters 27

28 Results and Discussion Cu-serum Cu-air 20 %of pg levels 10 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD 0 Congeners Figure 4 Comparison of dioxins levels in ambient air and serum of workers in copper smelters 28

29 Results and Discussion EAF-serum EAF-air 20 Congeners Figure 5 Comparison of dioxins levels in ambient air and serum of workers in EAF plant 29 %of pg levels 10 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD 0

30 Conclusions After a month of cleaning or maintenance in a municipal waste incinerator, a significant increase in serum dioxins levels was observed in temporary workers. The increase was greater in workers who had never done this type of maintenance than in those with previous experience, especially for 2,3,4,6,7,8-HxCDF levels. 30

31 Conclusions These preliminary data show that employers and employees need to pay much more attention to occupational health hazards even in temporary workers hired for annual incinerator maintenance. 31

32 Conclusions The usage of personal protective equipments was suggested to effectively reduce the concentrations of serum dioxins. 32